In parenteral solution administration sets and many other types of medical equipment tubular hubs, needle-receiving luers, and the like are utilized which must be sealed in a sterile manner until ready for opening and use.
Accordingly, a semi-rigid tube is provided to fit over the hub or luer as a removable sealing closure, the semi-rigid tube having a bore which may define several spaced annular sealing members. These are generally semi-cylindrical in shape, extending in circumferential manner about the axis of the bore. The annular sealing members are proportioned to press against a rigid, cylindrical surface of the tube to be sealed, providing several annular seal lines when in place, and yet permitting removal by simply twisting and pulling of the rigid sealing tube.
Such an arrangement, however, has the disadvantage that it exhibits a very sensitive tolerance of only one or two thousandths of an inch. In other words, if the sealing caps happen to be made with an inner diameter which is off of specification by more than two or three thousandths of an inch, the caps may either not fit on the desired luer or other tube to be sealed, or they will fit so loosely that they will fail to perform the desired sealing function. Similarly, if the outer diameter of the luer to be sealed is out of specification for any reason by two or three thousandths of an inch, the same effect may happen.
The above also indicates that separately-designed and molded sealing caps must be provided for each type of luer or other tube to be sealed, even if the variation in outer diameter between the various types is only two or three thousandths of an inch.
Furthermore, tip protectors which utilize, in their inner diameter, semi-cylindrical, annular sealing rings may be very difficult to mold. It has been found experimentally that, referring to medical-type tip protectors exhibiting an inner diameter of about 0.27 inch, it has been exceedingly difficult to mold semi-cylindrical, annular sealing rings which are as much as 0.01 inch in radius, in that such large sealing rings tend to rip as they are being removed from the mold. The only way to accomplish this would be to substantially increase the draft angle of the mold, or to use a much softer plastic molding material than is customarily used in this type of operation.
An example of a tip protector using such semi-cylindrical annular sealing rings is shown in U.S. Pat. No. 3,889,673. Other annular sealing structures are shown in U.S. Pat. Nos. 3,101,841; 2,752,059; and 3,583,591.
In accordance with this invention, a tip protector is provided which is capable of being used to seal tubular parts which may have a substantial size variation. In the specific embodiment shown, the tip protector of this invention is capable of sealing tubular parts which vary in outer diameter by up to about nine percent. Accordingly, quality control problems in the manufacture of sealed parenteral solution administration sets and similar medical items is greatly simplified, and a single design of tip protector can be used with varying designs of tubular members to be sealed.
Furthermore, the annular sealing members utilized in this invention may have a length which is substantially greater than 0.01 inch, while being readily moldable without damaging of the annular sealing rings on removal from the mold, even when a normal draft angle or taper is used on the mold (for example two degrees), and when normally stiff plastic formulations such as low density polyethylene are used for molding the tip protectors of this invention.